Differential planar aperture antenna

Abstract

A planar differential aperture antenna that has a high gain and wide bandwidth at a millimeter wave band is provided. The differential aperture antenna has a cavity within it that has a height of roughly a quarter of a wavelength of the desired transmission band. The cavity is H-shaped, and has a cross shaped patch within the cavity that is fed differentially by two grounded coplanar waveguides. Two ends of the patch extend towards the ports on either side of the differential aperture antenna, and the other two ends of the patch extend into the cavity lobes, perpendicular with respect to the ports.

What is claimed is: 
     
       1. A differential aperture antenna, comprising:
 a pair of grounded coplanar waveguides; 
 a first port formed at a first free end of a first coplanar waveguide of the pair of grounded coplanar waveguides and a second port formed at a second free end of a second coplanar waveguide of the pair of grounded coplanar waveguides; 
 an H-shaped cavity formed on a ground surface between the pair of grounded coplanar waveguides, and a surface metal strip, wherein the cavity comprises lobes, wherein the lobes are substantially symmetric across an axis between the first port and the second port; and 
 a cross shaped patch within the cavity and above the ground surface comprising a pair of first arms that extend the lobes, respectively, and a pair of second arms that extend towards and connect to the first port and the second port, respectively, wherein the cross shaped patch is symmetric across the first axis and across a second axis between respective ends of the lobes, and wherein the first arms are longer than the second arms. 
 
     
     
       2. The differential aperture antenna of  claim 1 , wherein the cross shaped patch is fed by a pair of microstrip lines. 
     
     
       3. The differential aperture antenna of  claim 1 , wherein the cross shaped patch is fed by a pair of substrate integrated waveguides. 
     
     
       4. The differential aperture antenna of  claim 1 , wherein a transmission received by the differential aperture antenna is guided along the cross shaped patch as a surface wave to the H-shaped cavity. 
     
     
       5. The differential aperture antenna of  claim 1 , wherein a height of the ports and the cross shaped cavity is equivalent to a quarter of a wavelength of a transmission received by the differential aperture antenna. 
     
     
       6. The differential aperture antenna of  claim 1 , wherein the cross shaped patch comprises a metal patch. 
     
     
       7. The differential aperture antenna of  claim 1 , wherein an actual aperture is larger than a physical aperture formed by the first port and the second port. 
     
     
       8. The differential aperture antenna of  claim 1 , wherein a width of the H-shaped cavity and a length of the H-shaped cavity are longer than a wavelength of a transmission received by the differential aperture antenna. 
     
     
       9. The differential aperture antenna of  claim 1 , wherein the H-shaped cavity is also formed by metal vias between the ground and the surface metal strip. 
     
     
       10. The differential aperture antenna of  claim 1 , wherein the substrate is around 0.787 mm. 
     
     
       11. The differential aperture antenna of  claim 9 , wherein the cross shaped patch is communicably coupled to a differential output or input port. 
     
     
       12. A method, comprising:
 receiving, by an apparatus, a transmission between two waveguides of the apparatus comprising a first waveguide and a second waveguide, wherein the first waveguide comprises a first port formed at a first free end of the first waveguide, and wherein the second waveguide comprises a second port formed at a second free end of the second waveguide; 
 coupling the transmission to a cross shaped patch that is within an H-shaped cavity and across an opening of the first port from a ground plane, wherein the H-shaped cavity is formed on the ground plane between the two waveguides and a surface metal strip, wherein the H-shaped cavity comprises lobes that are symmetric across an axis between the first port and the second port, wherein the cross shaped patch comprises first arms that extend into the lobes, respectively, and second arms that extend towards and connect to the first port and the second port respectively, wherein the first arms are lon er than the second arms and wherein the cross shaped patch is symmetric across the first axis and across a second axis between respective ends of the lobes; 
 guiding the transmission as a surface wave along the cross shaped patch to the H-shaped cavity; 
 splitting the transmission into two parts; 
 guiding the two parts to respective ends of the cross shaped patch that extend into openings of the H-shaped cavity; and 
 exciting a uniform aperture field distribution in the H-shaped cavity based on the two parts of the transmission. 
 
     
     
       13. The method of  claim 12 , further comprising:
 coupling a differential transmission to the cross shaped patch at the second port; and 
 guiding the differential transmission along the cross shaped patch to the H-shaped cavity, thereby splitting the differential transmission into another two parts and guiding the other two parts to the respective ends of the cross shaped patch. 
 
     
     
       14. The method of  claim 13 , wherein the two parts of the transmission and the other two parts of the differential transmission are on opposite sides of the cross shaped patch. 
     
     
       15. The method of  claim 14 , further comprising:
 forming a virtual alternating current ground line between the two parts of the transmission and the other two parts of the differential transmission. 
 
     
     
       16. The method of  claim 13 , wherein the exciting the uniform aperture field distribution is based on the transmission, the differential transmission, and electromagnetic radiation associated with the transmission outside the H-shaped cavity. 
     
     
       17. A method for fabricating a differential aperture antenna, comprising:
 forming a pair of grounded coplanar waveguides that have two ports between respective ends of the grounded coplanar waveguides, wherein the two ports comprise a first port formed at a first free end of a first coplanar waveguide of the pair of grounded coplanar waveguides and a second port formed at a second free end of a second coplanar waveguide of the pair of grounded coplanar waveguides; 
 forming an H-shaped cavity on a ground surface between the pair of grounded coplanar waveguides, and a surface metal strip, wherein the H-shaped cavity comprises two lobes, wherein the two lobes are symmetric across an axis between the first port and the second port; and 
 forming a metal cross shaped patch in the H-shaped cavity opposite a ground plane, wherein the metal cross shaped patch extends into the two lobes and the two ports, wherein the cross shaped patch is above the ground surface, wherein the cross shaped patch comprises a air of first arms that extend into the lobes respectively and a pair of second arms that extend towards and connect to the first port and the second port, respectively, wherein the first arms are longer than the second arms, and wherein the cross shaped patch is symmetric across the first axis and across a second axis between respective ends of the lobes. 
 
     
     
       18. The method of  claim 17 , wherein a distance between the metal cross shaped patch and the ground plane is about a quarter of a wavelength of a transmission received by the differential aperture antenna. 
     
     
       19. The method of  claim 17 , wherein the forming the pair of grounded coplanar waveguides comprises forming the pair of grounded coplanar waveguides in electrical contact with the ground plane. 
     
     
       20. The method of  claim 17 , wherein the H-shaped cavity is also formed by metal vias between the ground surface and the surface metal strip.